Sounds like you have the same trouble as I have. I replaced the plug, cleaned the carby till it was shining, took the pump apart and tested the output, and still it has either limited power or starts and stops in a very short time. It just will not keep running under its own steam. I placed a rag soaked in methylated spirits over the carby and it started and ran longer, this says to me that the air/fuel mixture is very lean. How can you adjust the mixture on this? The only thing I haven't tried is a spare carby. Can anyone shed some light on this problem?
Kent
June 2008